01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium bowl, cream together softened butter and 1/2 cup sugar until light and fluffy. Add 2 cups flour and salt; mix until just combined. Press evenly into the prepared pan.
03 - Bake the crust for 18 to 20 minutes, until lightly golden.
04 - While crust bakes, whisk together 1 1/2 cups sugar, 1/4 cup flour, eggs, lemon juice, and lemon zest in a large bowl until smooth and fully combined.
05 - Pour the lemon filling carefully over the hot crust as soon as it comes out of the oven.
06 - Return to oven and bake for 15 to 18 minutes, or until the center is just set and no longer jiggly.
07 - Remove from oven and cool completely in the pan on a wire rack. Once cooled, lift out using the parchment overhang and cut into 16 bars.
08 - Dust bars generously with powdered sugar before serving.